For this discussion, the emphasis is to be on how we can use the information from the book to mitigate climate change and rising levels of CO2. We're looking for solutions, not debate about whether or not there is a problem. I'd like the discussion to be positive, helping people to make appropriate decisions, encouraging any step in the right direction. Off topic posts and anything that smells like trolling will be removed.

It's already been asked to what degree could carbon farming is a “solution”. As I've observed elsewhere, I don't think it's a solution, but a wedge. So, how big a wedge? This question is answered on page 37. Current CO2 concentrations in the atmosphere are around 407 parts per million (ppm), and rising worryingly fast: https://www.co2.earth/ (it will drop back a few points over the summer, before peaking at an even higher level next winter). If the hypothetical maximum quantity of carbon we can sequester in soil is in the region of the equivalent of 50ppm of CO2 (the figure given by Toensmeier), we expect to peak at 450ppm (which I think is looking increasingly optimistic as a result of the ongoing lies peddled by climate change deniers), and we need to return to a maximum atmospheric concentration of 350ppm, then the answer is “less than half”.

So, with that out of the way, what ideas make most sense in terms of maximising the size of that wedge?

I particularly like the section on homegardens and related matters (pp. 42-49). On the other hand, I think it's going to be difficult to extend the idea into industrialised societies, where people have left or been forced off the land by the intensification of agriculture and by the demands of the 1% for factory labour. These are incredibly diverse habitats by almost any standards, and my own forest garden plans would be comparable to a temperate or subtropical homegarden. There is an urgent need for research into planting lists and schemes for temperate and subtropical zones, as well as thought on the subject of how climate change will drive successional processes (something inadequately discussed in Toensmeier's earlier work (see http://www.permies.com/t/20162/books/Edible-Forest-Gardens-Volume-Dave and http://www.permies.com/t/41448/books/Winter-Read-Edible-Forest-Gardens).

One problem, and I want to come back to this, is weak research. There are good studies conducted on such systems in the tropics, but we know much less about how they might work in subtropical and temperate zones, especially in terms of carbon sequestration. I think it's a safe enough bet that they will sequester carbon, and there is some research that points in that direction, but it's clear that studies are needed.

Another is that this weak research has led us to a situation where we have some idea of the likely range of net primary productivity, and thus carbon sequestration potential, even if we need to work out the details, but we know very little about yields. Very few people in permaculture and/or growing what might be termed temperate homegardens have measured their yields, although I've seen plenty of anecdotal complaint about low levels of protein. I have no idea whether this is a result of high expectations (most people in developed nations consume too much protein), poor design or a problem inherent to the concept.

I reviewed one of the documents cited here: http://www.permies.com/t/56228/books/Permaculture-agroecology-design-movement-practice What is clear from this book and this reference is that the failure of permaculture to actually address a range of valuable scientific questions in relation to a number of agricultural practices may have set the establishment of good practice back years if not decades. This is something I think we need to be addressing as a matter of extreme urgency, and not continue to make inflated claims on the basis of limited or non-existent evidence:

I think one of this book's great strengths is how it informs the practice of agroecology as much as it informs the practice of permaculture, and may even lead to better sharing of information between the two. Given that my own thought is increasingly driven by the science and practice of agroecology, I'd be keen to see this happen. Agroecology began among poorer farmers, few of whom are Caucasian, and many of whom are women, while Permaculture has had a tendency to be driven by Caucasian males, often with a mentality informed by dominance over the rest of the planet. It's often asked where the women are in Permaculture, and I think this is a fair question. Toensmeier (p57-8) specifically talks about the empowerment of female farmers. He recognises there is a clear gender gap, a consequence largely of structural socio-economic issues that need to be addressed, both in the overdeveloped world and elsewhere.

As one of my digressions, I'd observe that Permaculture could do with an analysis informed by intersectionality theory, but that's a long post on another thread probably better written by someone who is not a white, cis, het male.

The main problem with extending this model further is the existence of the large farm, whether extensive or intensive. To me it underscores the need to push a social transformation as well as an agricultural one. As far as I can see the only way to make an extensive homegarden work would be some sort of collective model, perhaps a co-op.

Otherwise you run the risk of having a big landowner with some variant of serfdom, either with lots of economically desperate “volunteers” (or, in the short term, WWOOFers) or a similar arrangement with cheap wage slavery. Needless to say, this does not appeal.

If anything what this book has helped bring into focus is how the threats imposed by climate disruption, coupled with the socio-economic structures that brought it about, necessitate a complete revision not just of agriculture, but of society. As Naomi Klein argues, this changes everything. http://thischangeseverything.org/

I'd agree, and those changes are very radical.

As I've observed on another thread (http://www.permies.com/t/55829//Read-Carbon-Farming-Solution-Eric) carbon sequestration payments on a broad scale at the social cost of having the stuff in the atmosphere would a) break the bank and b) involve shovelling massive payments in the direction of rich land speculators, as well as violating the basic principles of how a fee-and-dividend scheme might work. This could be used as redistributive justice for those farmers in the developing world most likely to suffer most from a problem they often did least to cause, but without a different model you can bet it won't happen. Vigilance is necessary, because those same vested interests who caused the problem will certainly try to both shirk responsibility and do their level best to profit again from it.

The other problem with this model is that it would involve predicating paying to sequester carbon on pumping more of the stuff into the atmosphere. There is more on financing in part 5, so I think this is probably something to be returned to later.

A smaller-scale carbon-farming system would work where you can find a hectare or two for a family, although again a redefinition of the word family might be called for: this might not be two adults (whether heterosexual or otherwise) and 2.4 kids. Much may be learned here from cultures outside our own, and this may be one of those areas where we are limited by language and experience.

On a directly related note, I came across a concept recently of the “marriage co-op”, centred round a farm. The details of how this would work were not clear (it was in a work of futuristic fiction), but the notion seemed to involve several adults in some sort of marriage contract, with legal title to the farm inherited collectively by the children.

Needless to say, I can see why many conservatives are so freaked out over climate change: the realities mean not only dealing with the fact that their system has involved treating the atmosphere as a sewer (and soil as an endlessly renewable resource to mine the nutrients from and then dump the results into the sea, in complete contravention of even basic understandings of nutrient cycles) but that we also need radical social changes – because the main alternative to the above would involve state ownership of the means of agricultural (and by implication industrial) production: i.e. Communism. At the very least the broad-scale farms will need to be broken up or brought into collective production, whether owned by the community or by the state. Prior attempts at the latter have, of course, proved to be less than successful as an economic model.

As we continue to read and discuss this book, I'm liable to have little patience for those attempting to assert their entitlement either to the conventional ownership of broad swathes of land, the profiteering from the occupation of state-owned land or of the maintenance of the status quo more broadly. One of the places where I fundamentally disagree with Toensmeier is that we are going to need to see major changes in human diets, whether he or many others like it or not. Personally, I think that's a good thing, especially if it comes with a resurgence of local and regional culinary traditions, and more sustainable ways of relating to other humans and the rest of the planet.

In fact, this is a point where I see a contradiction. He is keen for people in the Global South to change their diets, but seems keen to allow a lot of meat production, so that people in the Global North don't have to change theirs.

On page 27 he talks about livestock, and I'll come back to this with some comments on Part 2 at a later date. It's no secret to those who have read my posts elsewhere that I think that the keeping of livestock is largely, if not completely, incompatible with permanent agriculture. I followed his main reference on page 27 back through the literature (his reference led to another), and found it here: https://nicholasinstitute.duke.edu/sites/default/files/publications/ni_r_10-04_3rd_edition.pdf This is a non-peer-reviewed document which seems to support the hypothesis, but it involves the replacement of native grasses with higher-yielding varieties (which completely contradicts claims by ranchers, even ones practicing mob stocking or what they misleading call holistic management, about restoring prairie). Intensification of pasture production through these processes may be negative. It may be, but the conditions under which it may be are complicated, and the research is often contradictory.

What is also clear is that many of the “success” claims about soil as a result of grazing may be the result of any of a combination of several other practices, such as cover cropping and no-till practices (for instance this study found “that the relatively low rate of grazing did not significantly affect the amount of organic matter in soil and did not cause soil compaction” http://onpasture.com/2015/12/07/no-harm-to-soils-when-cattle-graze-cover-crops/ - obviously this is bad because we want systems that increase the amount of organic matter), as well as supplementary feeding (eg Savory and Salatin) and the addition of compost (eg the Marin project: http://www.marincarbonproject.org/home – which is also bad because here we have a system using scarce compost for minimal return on carbon sequestration).

Rates of sequestration are lowest where existing carbon levels are highest, which means that carbon sequestration is more likely to be offset by nitrate and methane emissions. Improving carbon sequestration rates on low-carbon grasslands depends on reducing the stocking rates and, because such grasslands tend to be less productive, using supplementary feeding. That said, the research in this regard is also ambiguous: several studies have found that this practice reduced soil carbon.

In other words, grazing can, under certain circumstances, result in carbon sequestration (and what you end up with is not prairie), but it's tricky to generalise, and you are generally better off doing something else (usually involving planting trees). Crucially, because of that vast area we would, in effect, be wasting vast areas of land (about 26% of the world's total land area, according to the FAO) on pasture sequestering dismally low quantities of carbon when we could be doing something more efficient with it – either turning it over to wildlife habitat or converting it to some form of agriculture that sequesters more carbon and produces more food because it's not passed through a herbivore first.

It is true that cows can convert more of the net primary productivity into food for them than we could trying to do it ourselves. The main reason for this is because pastures are deliberately sown with species with high net primary productivity, not high yield. Multistrata agroforests provide higher NPP (yields are, as I say, a more complicated problem, worsened by the refusal of many permaculturalists to investigate the question). Many annual crops provide higher yields, especially among the legumes.

In addition, the citation refers to practices in the US, on soil types found in the US, under their climate conditions. It seems to be difficult to generalise it further. Research elsewhere suggests very high net emissions for grazing on soils with a high carbon content. Sadly, Toensmeier doesn't mention this: http://www.sciencedirect.com/science/article/pii/S0306919212000942

This is a subject that might (actually, probably will) bear revisiting later in the book, but it does emphasise the point that Toensmeier's literature survey may have been lacking. I'm not yet sure how widespread this problem is, or whether he's gone into more depth in terms of the research in chapter 7 (a quick read-through showed mixed results).

Another caveat relates to a comment on pages 15-16 on how reductions in crop yields as a result of climate change may be offset by a couple of per cent as a result of increased atmospheric CO2. I think we need to be cautious of this figure and of other claims related to increased plant growth as a result of these increases (a myth peddled by the fossil fuel industry and repeated ad nauseam by deniers). It's true that we are seeing some small increases in the global rate of photosynthesis, but this is where CO2 is the main limiting factor. As soon as the local environment finds another limiting factor (water and either macro- or micronutrients) this increase will slow or stop. He's not wrong, but the reality is more nuanced.

Another question about yields is raised on page 57. At a practical level I want to know whether those lower yields for perennial crops are offset by additional yields in the understorey: I may end up with fewer apples than I would in a monoculture orchard, but I also want to know the implications for harvests from the understorey. Chapter 6 in Part 2, which I'll come back to in a later thread, talks about annual cropping systems: these can be integrated with perennials, and this may be a design question.

So, second impressions are that this is a good but flawed (although some of those flaws could be mere illusion: more study is needed) book that could have been twice the length, much more controversial, but should probably be on a supplementary but not necessarily core reading list for both students of permaculture and of agroecology.

I think there are issues with his research base. Some of them are unavoidable: the research isn't there. Some of them have to do with outdated material. For example, he cites Mark Lynas's Six Degrees: Our Future on a Hotter Planet: Lynas's work on warming was comprehensive, much more so than the basis of some of his more recent pronouncements http://www.theecologist.org/campaigning/2987655/gmo_lobbys_false_claims_to_defend_gm_oilseed_against_deformed_butterfly_findings.html, but the bottom line is that he's still a hack journalist, and the work is out of date; it's not wrong, but some of the uncertainties have been resolved in the nine years since it was published, which implies he could have found a better source. Sometimes I think he overstates or understates research conclusions in order to support his own conclusions: this is rarer, but the fact the book is referenced does mean it's possible to check, and this is a great strength.

Wow Neil. I love your post. It is a real privilege to do this read-along with you.

I like how Toesmeier says right from the start that carbon farming is just one of many things humanity needs to do if we hope to reduce the effect of climate change. Seeing carbon farming as part of the solution, and not the only solution is an important step. I worry if we start carbon farming, humanity might get lazy and stop looking for more things we can do to limit our effect on the world. The wedge metaphor is an excellent one.

One problem, and I want to come back to this, is weak research. There are good studies conducted on such systems in the tropics, but we know much less about how they might work in subtropical and temperate zones, especially in terms of carbon sequestration. I think it's a safe enough bet that they will sequester carbon, and there is some research that points in that direction, but it's clear that studies are needed.

I was wondering this too. I don't live in the tropics, so how can I know what methods work for me? Also, I was curious if some systems that have minimal effect at sequestering carbon at tropical latitudes, would have more effect in a temperate zone? Sunlight is very different as you move away from the equator, and since it is essential for photosynthesis, wouldn't we need to study the same systems at different latitudes to see how they work? As you know, this isn't my academic area, so maybe it has been done already. From my limited point of view, it seems the obvious step.

... second impressions are that this is a good but flawed (although some of those flaws could be mere illusion: more study is needed) book that could have been twice the length, much more controversial, but should probably be on a supplementary but not necessarily core reading list for both students of permaculture and of agroecology.

I feel it's a very difficult balance when writing anything. His audience is the general public, accademics and policy makers... and how to say this without being insulting.... hm, sometimes an author sacrifices depth and accuracy in order to reach the largest audience possible. This book to me is a lot like Carbon Farming 101 - the introduction. It makes a good starting place, and there are all sorts of ideas and references that if something catches our fancy, we can research it in depth. I really hope Toesmeier runs with this idea, and writs a few more indepth books on the topics that have the strongest bennifit, like the year 2 and year 3 classes.

I'm almost finished the section so I'll have more to say soon.

One question I'm still unsure about - and maybe this will become clear as I read the book. When we talk about carbon farming, it seems to focus on sequestering the carbon in the soil. The above-ground part of the plant also uses carbon, so would it be possible to use this to quickly catch some atmospheric carbon? I don't imagine it would be enough in and of it'self, but maybe it would be a useful addition to sequestering it in the soil. For example, coppicing some trees. When cut off at the ground, the tree grows more rapidly than it would when started from seed. We use this coppice wood (thus lowering the demand on other forests that are more efficient at absorbing carbon) and keep the coppice wood in use as long as possible? It's not a well-formed idea yet, and it certainly wouldn't be enough to make a huge difference, but would it help? What do we think about above-ground carbon sequestration?

I need to get back to reading the book, but I just wanted to say (again) how much I enjoyed your post, Neil.

R Ranson wrote:. I was wondering this too. I don't live in the tropics, so how can I know what methods work for me? Also, I was curious if some systems that have minimal effect at sequestering carbon at tropical latitudes, would have more effect in a temperate zone? Sunlight is very different as you move away from the equator, and since it is essential for photosynthesis, wouldn't we need to study the same systems at different latitudes to see how they work? As you know, this isn't my academic area, so maybe it has been done already. From my limited point of view, it seems the obvious step.

One of my problems is the lousy state of research into what might be termed temperate homegardens, especially as regards yields. I expect this to be a focus both of my reading and several future posts, provided I can get away from arguing with ranchers looking for an excuse for business as usual. Yes, we do need this research. We need to understand best practice, we need to know carbon sequestration rates, net primary productivity, yields, protein:carbohydrate ratios and so on. This means we need a lot of Permies who are better educated about and able to conduct scientific research in their habitats.

I'm working on it.

I'm almost finished the section so I'll have more to say soon.

I'm looking forward to it. I'd like to get a good discussion going.

One question I'm still unsure about - and maybe this will become clear as I read the book. When we talk about carbon farming, it seems to focus on sequestering the carbon in the soil. The above-ground part of the plant also uses carbon, so would it be possible to use this to quickly catch some atmospheric carbon? I don't imagine it would be enough in and of it'self, but maybe it would be a useful addition to sequestering it in the soil. For example, coppicing some trees. When cut off at the ground, the tree grows more rapidly than it would when started from seed. We use this coppice wood (thus lowering the demand on other forests that are more efficient at absorbing carbon) and keep the coppice wood in use as long as possible? It's not a well-formed idea yet, and it certainly wouldn't be enough to make a huge difference, but would it help? What do we think about above-ground carbon sequestration?

This is talked about. In fact, measuring aboveground carbon is easier than measuring soil carbon, in part because there are no standardised methods for the latter. There are problems with the permanence of both, and there are many concerns that worsening warming may result in soils losing carbon at a greater rate. There is a case for storing carbon as wood or biochar, but there are issues with scaling it up and of the loss of other soil nutrients. As with so many of these issues, it's complicated.

Neil Layton wrote:It's already been asked to what degree could carbon farming is a “solution”.

I think I've taken a totally different understanding from the title, Neil. I think he's saying he's offering a solution to the question of carbon farming. As in "How do we do carbon farming?".
I agree about it being a wedge, or a percentage, of a total solution to reduce atmospheric CO2 , as you say 50% is a pretty big wedge and one that demands serious consideration, but it's also true that it's not going to magic the problem away. Which leads me to my next point.

I also completely agree regarding the issue of keeping the carbon in the ground. Quite simply, if we don't, we're toast. But PLEASE for us lesser mortals would you spilt your posts up into discussions of the book and discussions around the wider issues!
My brain needs a little focussing onto what is actually possible for me to do, and since I'm not currently over-burdened with exclusive mining rights to unexploited hydrocarbons, getting a better idea of what kind of farm I should build is the reason I bought the book.

I particularly like the section on homegardens and related matters (pp. 42-49). On the other hand, I think it's going to be difficult to extend the idea into industrialised societies, where people have left or been forced off the land ...

This part got me pretty inspired to be honest. I also really liked that it shoved the solution (or part of it anyway) firmly back into the garden. As Geoff Lawton says "You can solve all the worlds problems in a garden."

Rus Williams wrote: But PLEASE for us lesser mortals would you spilt your posts up into discussions of the book and discussions around the wider issues!
My brain needs a little focussing onto what is actually possible for me to do, and since I'm not currently over-burdened with exclusive mining rights to unexploited hydrocarbons, getting a better idea of what kind of farm I should build is the reason I bought the book.

Sorry. I did discuss this with one of the mods, and offered to split it up, and she advised me to leave it in one piece. I can't please everyone when they want two contrary things.

One question I'm still unsure about - and maybe this will become clear as I read the book. When we talk about carbon farming, it seems to focus on sequestering the carbon in the soil. The above-ground part of the plant also uses carbon, so would it be possible to use this to quickly catch some atmospheric carbon? I don't imagine it would be enough in and of it'self, but maybe it would be a useful addition to sequestering it in the soil. For example, coppicing some trees. When cut off at the ground, the tree grows more rapidly than it would when started from seed. We use this coppice wood (thus lowering the demand on other forests that are more efficient at absorbing carbon) and keep the coppice wood in use as long as possible? It's not a well-formed idea yet, and it certainly wouldn't be enough to make a huge difference, but would it help? What do we think about above-ground carbon sequestration?

There's a bit about this in chapter 3 hidden in table 3.2 on page 32. The values are for tropical coppice, not temperate, but the tons per hectare over the lifetime is high.

So if I look at figure 2.1 on page 22, the assertion that 2/3 of total carbon of an agroforestry system is below ground (in soil carbon mainly) then it seems to make sense that starting a long-lived coppice system would sequester a chunk of carbon quite nicely in the soil and using the coppice wood is just a natural carbon flow.

I'm not reading the book because I don't have it, but I do have a question relating to carbon sequestration in temperate zones versus tropical - as I understand it, photosynthesis is relatively inefficient in the tropics because of intense sun and high temperatures, so relatively less CO2 is being drawn from the atmosphere in tropical zones compared to temperate zones. Is this true? Or am I misremembering something?

Tyler Ludens wrote:I'm not reading the book because I don't have it, but I do have a question relating to carbon sequestration in temperate zones versus tropical - as I understand it, photosynthesis is relatively inefficient in the tropics because of intense sun and high temperatures, so relatively less CO2 is being drawn from the atmosphere in tropical zones compared to temperate zones. Is this true? Or am I misremembering something?

I would like to know this too.

I'm completely scattered with other things, but just finished a big deadline, so I'll be re-reading this section. The information might be in there and I missed it with all my distractions.

As with all such things, it's complicated. The main complications are saturation and limiting factors.

If there is not enough of one factor, growth will be inhibited. At some point any more of that factor won't help.

Plants require about 17 chemical elements plus light in order to grow. They also need to be in the right temperature range (for most practical purposes between about 10C and 30C: below 10C and photosynthesis more or less stops because it's not warm enough, and above about 30C the enzymes involved denature). For much of the day in the tropics temperatures exceed 30C.

That said, on most days temperatures do drop below about 30C. At that point the main limiting factor is water. Too much water inhibits ion transport. Too little means photosynthesis can't take place. In some cases the key to this is irrigation at the right time of day. In some cases it depends on the photosynthetic pathway being used by the plant (C4-pathway species such as maize are able to continue photosynthesis at a higher temperature and with less water than C3 pathway species such as wheat).

In the case of light, there is a point at which the plant can't use more light, and this is common in the tropics. That does not mean the plants grow less well: it just means that there is more than enough light. Conversely in temperate zones the limiting factor during the winter during the day is not necessarily light, but often heat. On the other hand, increasing carbon dioxide and increasing heat will not necessarily make growing crops much easier, because it's often a close call between light and heat. The heat (and evaporation) may go up in the tropics, (making growing crops increasingly difficult), but the limiting factor in temperate zones may become light, not heat. Light can be taken to be a constant, depending on latitude (and, to a point, cloud and suspended particulates).

So, for example, where you are in Texas, Tyler, light is likely to be often saturated, but you're likely to be limited by either water or one or more soil nutrients, depending on how overgrazed the soil is.

Carbon dioxide is only limited in greenhouse situations. This is unlikely to saturate, but sooner or later plants will still run into another limiting factor, but which one depends on latitude, the availability of water, and soil nutrients.